moke
contains microscopic particles, called particulate matter, which are
smaller than 10 microns in size or about one fifth of the thickness of a
human hair. Even finer particulate matter, smaller than 2.5 microns in
diameter, are also present.

Air quality effects of smoke:

Reduced visibility

Huge emissions of particulate matter smaller than 2.5 microns, known
as PM2.5, are pumped into the air and are responsible for the smoky haze
that spreads over wide areas during a fire

Also, these particles can be inhaled into the tiny air sacs of our lungs
and cause permanent damage

Particulate Levels Set By the EPA

The EPA set a PM2.5 standard of 65 micrograms per cubic meter averaged
over 24 hours.

PM2.5 levels are measured locally by a portable particulate monitor.

The PM2.5 readings are then converted to the State Pollutant Standards
Index (PSI) and used to give guidance on health and advised activity levels.

Federal Health Standard

Health Advisory for Ozone: Unhealthy

Stage 1 Alert: Very Unhealthy

Stage 2 Warning: Hazardous

Stage 3 Emergency

PSI 100

PSI 150 and Above

PSI 200 and Above

PSI 300 and Above

PSI 400 and Above

People sensitive to air pollution should reduce physical
exertion and limit outdoor activity.